Flower of Abelmoschus Manihot (L.) Medic is the dried flower of Abelmoschus Manihot (L.) Medic belonging to plants of Abelmoschus of malvaceae, the Abelmoschus Manihot (L.) Medic was first recorded in the “Jiayou Materia Medica”, it is widely distributed with abundant resources. It is recorded in the “Compendium of Materia Medica” that, the flower of Abelmoschus Manihot (L.) Medic, which is sweet in smell, cold and slippery in nature and non-toxic, is mainly used for treating dribbling urination and hastening parturition, enables the patients suffering from malignant sore pus and having not being cured for a long time to recover from illness after applying its powder, and is an effective drug for treating illness of sores, and used for reducing carbuncle swelling and treating scald due to immersion in oil and boiling water and fire burns, etc. According to modern medicine, the main active ingredients of flower of Abelmoschus Manihot (L.) Medic are ingredients of flavones, current research on the chemical components is also concentrated in the total flavone of flower of Abelmoschus Manihot (L.) Medic (TFA) and monomer thereof. Seven monomers of flavones have been isolated and identified since 1980s. Studies demonstrate that the isolated monomers can reduce proteinuria and red blood cells in urine, alleviate tubulointerstitial lesions, eliminate oxygen free radicals, increase immune adhesion of red blood cells, promote transportation and removal of human circulating immune complexes (CIC), regulate immune function of cells and inhibit the degree of humoral immune response, thereby alleviating CIC-mediated renal injury and improving the function of kidney, so that the purpose of treating chronic kidney disease (CKD) can be achieved.
Pharmacological studies show that compounds of flavones are the main bioactive ingredients in flower of Abelmoschus Manihot (L.) Medic. Further chemical studies show that, the following nine compounds are in high contents in the compounds of flavones (or referred to as total flavone) in flower of Abelmoschus Manihot (L.) Medic: hyperin, isoquercetin, quercetin-3′-glucoside, gossypetin-3′-glucoside, myricetin-3-glucoside, quercetin-3-robinobioside, gossypetin, myricetin and quercetin, the formula of the nine compounds are as follows:

Current methods for preparing the total flavone extract of flower of Abelmoschus Manihot (L.) Medic can be summarized into the following three methods.
1. Extraction is performed with water or alcohol first, and the extract after recovering of the solvent is suspended in water, then extraction is performed with chloroform, ethyl acetate and n-butanol respectively, and the resulting extract is divided into several parts, and then chromatography and isolation is performed with a silica gel column or Sephadex column to obtain a single component material.
2. Extraction is performed with ethanol, the extracts are combined and filtered and the filtrate is concentrated, then the concentrated liquid is diluted with an appropriate amount of water, and gradient elution is performed with the alcohol aqueous solution through a macroporous resin column or polyamide column, then the eluate is concentrated, dried and pulverized to obtain the total flavone extract, this method can refer to the method for preparing the total flavone extract of flower of Abelmoschus Manihot (L.) Medic disclosed in the patent application for invention with application No. 200410035741.X.
3. Extraction is performed with ethanol and the extracts are combined, the extract is concentrated under reduced pressure to become an extractum having the specific gravity of 1.13-1.16 at 60° C., and the extractum is added with boiling water several times to be dissolved, and let to stand and filtered, and chromatography is performed on the filtrate by a macroporous adsorption resin column or polyamide column, then the column is eluted with methanol and the eluate is collected; the eluate is concentrated under reduced pressure and dried in vacuum to obtain the crude total flavone extract of flower of Abelmoschus Manihot (L.) Medic; then the crude total flavone extract is refined and extracted with ethyl acetate-ethanol, and the solvent is recovered from the extract, then the extract is dried under reduced pressure or in vacuum to obtain the total flavone extract of flower of Abelmoschus Manihot (L.) Medic, this method can refer to the method for preparing the total flavone extract of flower of Abelmoschus Manihot (L.) Medic disclosed in the patent application for invention with application No. 200610097615.6.
The kind and content of compounds of flavones contained in the extract extracted by different methods are different, in other words, different compositions and weight ratios of total flavones lead to different pharmacological activity and great difference in potency, which means that the substance extracted by each extraction method is a new substance (composition). Although it is deemed that compounds of flavones are active ingredients currently, it has not been determined in the prior art that which compound(s) in these compounds of flavones is(are) the main active ingredient(s), the present invention determines the main compounds of flavones by a large number of experiments. The present invention further optimizes the weight ratio among the main active ingredients, for the contents of flavones in the current total flavone extract of flower of Abelmoschus Manihot (L.) Medic, gossypetin-3′-glucoside<quercetin-3′-glucoside≤isoquercetin, and the content of gossypetin-3′-glucoside is usually half of that of isoquercetin or quercetin-3′-glucoside, in the total flavone extract of flower of Abelmoschus Manihot (L.) Medic in the present invention, the content of gossypetin-3′-glucoside is basically over 2 times that of isoquercetin or quercetin-3′-glucoside, meanwhile, the extract of the present invention also has better effects in the treatment of kidney diseases.
In view of the above, there is urgent need to provide a total flavone extract of flower of Abelmoschus Manihot (L.) Medic with definite effective ingredients, better efficacy and stability, safety and reliability, reasonable and feasible process, and stable quality, and preparation method thereof, which is suitable for the large-scale production of enterprises, solving the problem that the flower of Abelmoschus Manihot (L.) Medic formulation is taken in high dose to provide convenience and benefits for patients.